(1) Field of the Invention
This invention relates to an X-ray radiographic apparatus for facilitating gastrointestinal examination in human medical care. The apparatus includes a diagnostic table, an X-ray emitter for emitting X-rays to the diagnostic table, an X-ray high voltage unit for generating varied currents to switch a quantity of X-rays emitted from the X-ray emitter between a monitoring condition and a photographing condition, a filming mechanism mounted in the diagnostic table for photographing X-ray images based on the X-rays emitted from the X-ray emitter, an image intensifier attached to the diagnostic table for convertinq the X-ray images to visible light images, a CCD (charge coupled device) camera unit for converting the visible light images to image signals, and a monitor unit for receiving the image signals from the CCD camera unit to display the visible light images converted by the image intensifier.
(2) Description of the Prior Art
The X-ray radiographic apparatus allows observation on a monitor unit, and film photography carried out with selected timing. Normally, a doctor or other person observes X-ray penetration images on the monitor unit. When a desired image appears on the monitor unit, the doctor or other person gives a photographing command to take this image on photographic film. At the time of this photo taking, the film is transported to a front surface of an image intensifier, and the quantity of X-rays is increased to expose the film. The X-rays having penetrated the film enters the image intensifier. If the X-rays in the increased quantity were not modified, the CCD image pickup device of the CCD camera unit connected to the image intensifier would be saturated. Conventionally, an optical diaphragm is interposed between the image intensifier and CCD camera unit to reduce light at photographing times. In this way, images may also be observed on the monitor unit while the images are photographed, without saturating the CCD image pickup device.
However, the optical diaphragm used heretofore for reducing light is a mechanical device which has the disadvantages of poor responsibility and durability due to mechanical motion.
Further, with the conventional X-ray radiographic apparatus, the image appearing on the monitor unit during photo taking is based on X-rays intended for film photography. The image is eliminated from the monitor unit immediately upon completion of film photography. Thus, the conventional apparatus also has the disadvantage that an image actually photographed cannot be confirmed on the monitor unit following the photo taking.